UV, Violet, or IR which is best for burning?

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I'm trying to decide what my next laser should be. I have green and red, waiting for my arctic. Does IR burn? 808nm vs 1342nm. So many questions in my mind. I'm looking for max burn here!. any suggestions?

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I think I remember reading somewhere or just hypothesizing this myself, but I believe a lower wavelength laser can also focus down to a smaller point. Which from what I understand, is why a blu-ray disk can hold so much more data than a DVD. Because the smallest focus point of the 405nm laser is maybe a 1/5th the size of a DVD laser's smallest focus point, thus giving it more surface area on the disk to read from. And enabling the BD disk to hold much more data than a conventional DVD.

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All other things being equal, a shorter-wavelength laser can be focussed to a smaller spot. This translates to a higher energy density, and better burning ability. Other factors (beam size and shape) matter also, but wavelength has a major effect on minimum spot size.

If you start with 405nm and 808nm beams of the same size, focused with the same lens(es), the 405nm beam will make a spot 1/2 the diameter of the 808nm beam. That means the surface area of the spot will be 1/4, and the power level 4 times as high, at the same laser power level.

445nm packs a lot of power in a 5.6mm frame. but it is only good for burning up close. if you want distance burning go for violet. ppl can light matches and pop balloons from over 40 feet with about 500mw

I think I remember reading somewhere or just hypothesizing this myself, but I believe a lower wavelength laser can also focus down to a smaller point. Which from what I understand, is why a blu-ray disk can hold so much more data than a DVD. Because the smallest focus point of the 405nm laser is maybe a 1/5th the size of a DVD laser's smallest focus point, thus giving it more surface area on the disk to read from. And enabling the BD disk to hold much more data than a conventional DVD.

But the focus point can get that small with the lenses we use right?... or at least smaller than a 650nm with the same lenses? Cause my 405nm <100mW lasers can rip through stuff that my >150mW 650nm could never even dream about doing. Ever since I got my first 405nm, I always thought that the focus point looked so much smaller than my 532 and 650nm lasers when I focused them down. Although I suppose that could have just been the result of the color making it 'seem' smaller (with goggles on of course).

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Also .. if you say blue photon has more energy then red ones, it just means that you will need less blue photons for same power. But 200mW of blue will have exactly same burning capacities as 200mW of red, putting aside different absorption properties of burned material and focus.
Focus imho will make little difference, as those small lens do not reach diffraction limit. There are other distortions with larger effect. For 1W 445 diodes for example their elliptical beam will focus much worse then common red lasers.
For burning skin (and eyes !) 445 will burn much more, as it is several times better absorbed. Still my 200mw red burns me happily.

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Ah, a classic question, and I answer it with another question: which color car is the fastest? I personally think red cars are faster than blue cars, what do you guys think? Yellow cars are pretty fast too though. Not a perfect analogy, as color does matter somewhat in some cases for laser "burning"/cutting, but it does get at the heart of the issue, that color doesn't decide burning capability, it more depends on other factors.

really though, it depends what you want to burn, as you need the object to absorb as much light as it can. In most applications that hobbyists encounter, 405nm is absorbed very well, even by many white things around us in every day life, so it seems the best. For some objects, IR may be better. In general, of the visible wavelengths, it seems that the longer 405nm light is absorbed by more objects, but for some objects the extra power available in 445nm may overcome the absorption difference, so it really just depends on what you're trying to do. There is no single answer.

As far as focusable size, it is true that lower wavelengths have smaller theoretical focal limits, but we never get anywhere neat those theoretical limits in practical usage with one single tiny lens straight off of the ugly output of a laser diode. It's largely a moot point. Like yes, a Ferrari may go faster than a Porsche, but I have neither, so why does it really matter?